The present invention relates to a fuel pump and, in particular to a gasoline use fuel pump suitable for an in-cylinder direct injection system used for in an internal combustion engine.
In an internal combustion engine, in particular in a gasoline internal combustion engine for use in an automobile, recent efforts have been made to improve fuel consumption, reduce harmful exhaust gas and improve driveability (a response for a drive condition changing) etc. of the automobile, by seriously studying a practical application of an in-cylinder direct injection system.
In the in-cylinder direct injection system of the gasoline internal combustion engine, a fuel delivery source is indispensable to directly inject the gasoline into a cylinder of the gasoline internal combustion engine. Since the gasoline injection into the cylinder is required even during a compression cycle of the engine, from the above stated fuel delivery source, it is necessary to delivery the fuel having a high pressure of some 30-100 kg/cm.sup.2.
The gasoline to be delivered has an extremely small viscosity property and also has an inferior lubrication property in comparison with general use oil such as engine oil.
As a result, since the leakage of the gasoline from a compression part is large and it is difficult to compress the gasoline at a high pressure, a lubrication property in a fuel pump load supporting member (for example, a bearing member) is injured.
At the present time, the bearing member cannot be expected to have a needed life time under the gasoline environment.
Further, in a sealing member of a rotative shaft for the fuel pump construction, at the present time, it is extremely difficult to expect sufficient reliability of the sealing member under the gasoline environment.
From the above stated circumferences, a fuel pump is disclosed in, for example, Japanese patent laid-open publication No. 209,981/1992.
This conventional fuel pump construction attempts to overcome the above stated problems about the low gasoline viscosity property and the difficult compression to the high pressure.
Namely, in the above stated conventional fuel pump construction using the secondary fluid having the high viscosity and the high lubrication property, an increased pressure in the fluid is easily performed.
The gasoline is raised in pressure through a pressure transfer member (in this case, a bellows) and, in addition to the above, the lubrication in the load supporting member such as a bearing member is performed using the secondary fluid. Further, the secondary fluid becomes a sealing material for sealing a rotative shaft.
However, in the above stated conventional fuel pump construction, since the pressure transfer member is necessary for every compressing cylinder of the fuel pump, the number of components undesirably increases. Further, from a structural aspect in case of an employment of a multi-cylinder structure, the apparatuses must be arranged in an axial direction, thereby causing a problem where an axial direction dimension of the fuel pump construction increases.
In the above stated in-cylinder direct injection system for use in the internal combustion engine, from the viewpoint of the volume control accuracy of the injection fuel, the response for control, optimizing injection timing, it is desirable to control an injector electronically. To serve the above purpose, a small fluctuation of a delivery fuel pressure is required.
Accordingly, a large number of the compressing cylinders is desirably provided and, in case of the multi-cylinder structure, a compact size fuel pump structure should be realized.
An object of the present invention is to provide a multi-cylinder fuel pump of compact size.
Another object of the present invention is to provide a fuel pump wherein an improved lubrication property of a fuel pump load supporting member is achieved.
A further object of the present invention is to provide a fuel pump wherein a reliability property in a sealing structure for a rotative shaft can be increased.
A further object of the present invention is to provide a fuel pump wherein a lowering phenomenon of volume efficiency caused from low viscosity in fuel such as a gasoline can be fully realized by a compact multi-cylinder type fuel pump structure.
A further object of the present invention is to attain an increase of discharge flow amount of the fuel. According to the present invention, a fuel pump comprises a rotational shaft driven by a rotation of an internal combustion engine and a swash plate mounted on the rotational shaft in which a rotating motion of the rotational shaft is converted by an axial inclined gyration motion, and fuel is pressurized and compressed to raise pressure in accordance with an axial direction motion component of the swash plate. A rotating motion converting mechanism for converting the rotating motion of the rotational shaft to the axial inclined gyration movement is isolated through a flexible isolating member.
According to the present invention, a fuel pump comprises a rotational shaft for transmitting rotation from an outside motive source, a swash plate fixed on one end of the rotational shaft and for rotating together the rotational shaft and having a different normal direction face from an axial direction of the rotational shaft, plural pressurizing chambers for pressurizing fuel, and a rotating motion converting portion for converting a rotating motion of the rotational shaft to a reciprocating motion of the swash plate and for transmitting the reciprocating motion to the pressurizing chamber. The rotating motion converting portion is isolated through a flexible isolating member.
According to the present invention, a fuel pump comprises a rotational shaft for transmitting rotation from an outside motive source, a swash plate fixed on one end of the rotational shaft and for rotating together the rotational shaft and having a different normal direction face from an axial direction of the rotational shaft, plural pressurizing chambers for pressurizing fuel, and a rotating motion converting portion for converting a rotating motion of the rotational shaft to a reciprocating motion of the swash plate and for transmitting the reciprocating motion to the pressurizing chamber. A sliding and contacting portion formed between the swash plate and the rotating motion converting portion and the swash plate are isolated through a flexible isolating member.
According to the present invention, a fuel pump comprises a body, a rotating shaft penetrating mounted on the body, a swash plate member provided on an interior portion of the body and mounted on one end of the rotating shaft, a motion converting portion for converting a rotating motion of the rotating shaft to an inclined gyration movement, a pump mechanism portion opposite arranged to the swash plate member and having plural pistons which slide and contact the swash plate member, a first fluid section for receiving a first fluid which is pressurized according to an axial direction motion by the swash plate member, and a second fluid section adjacently provided on the first fluid section and for receiving a second fluid, and the second fluid section for including the motion converting portion, viscosity of the second fluid in the second fluid section is larger than viscosity of the first fluid in the first fluid section.
According to the present invention, a fuel pump comprises, a body having an opening portion at one end, a rotating shaft penetratingly mounted on the body, a swash plate member provided on an interior portion of the body and mounted on one end of the rotating shaft, a motion converting portion for converting a rotating motion of the rotating shaft to an inclined gyration movement, a pump mechanism portion provided on the opening portion of the body and opposite arranged to the swash plate member, and the pump mechanism portion having plural pistons which slide and contact to the swash plate member, a first fluid section provided on a side of the pump mechanism portion and for receiving a first fluid which is pressurized according to an axial direction motion by the swash plate member, and a second fluid section adjacently provided on the first fluid section and for receiving a second fluid, and the second fluid section for including the motion converting portion, viscosity of the second fluid in the second fluid section is larger than viscosity of the first fluid in the first fluid section.
According to the present invention, a fuel pump comprises a body having an opening portion at one end, a rotating shaft penetrating mounted on the body; a swash plate member provided on an interior portion of the body and mounted on one end of the rotating shaft, a motion converting portion for converting a rotating motion of the rotating shaft to an inclined gyration movement, a pump mechanism portion provided on the opening portion of the body and opposite arranged to the swash plate member, and the pump mechanism portion having plural pistons which slide and contact the swash plate member, a flexible isolating member provided in the interior portion of the body, a first fluid section provided on a side of the pump mechanism portion and isolated by the flexible isolating member, and the first fluid section for receiving a first fluid which is pressurized according to an axial direction motion by the swash plate member, and a second fluid section adjacently provided on the first fluid section and isolated by the flexible isolating member, and the second fluid section for receiving a second fluid and for including the motion converting portion, viscosity of the second fluid in the second fluid section is larger than viscosity of the first fluid in the first fluid section.
The basic concept of the present invention for solving the aforementioned problems is that the motion converting portion for giving the reciprocating motion of the pump compressing portion is enclosed by the flexible isolating member. Further another approach used in the present invention is that the lubricating oil is enclosed in the flexible isolating member.
In the present invention, the basic system of the fuel pump has the swash plate system, and this swash plate system is suitable to form both the small size and the multi-cylinder type fuel pump.
In the present invention, only the swash plate is caused to have the inclined gyration movement. The rotating motion preventing member is selectively provided on the swash plate, thereby to positively dissolve the rotation force acting on the flexible isolating member.
Further, because the rotation direction strength of the flexible isolating member is fully processed, the above mentioned rotating motion preventing member is unnecessary, and as a result the number of the pump components are reduced.
The end portion of the flexible isolating member is formed to selectively cause the eccentric inclined gyration movement and the stress easing generated on the flexible isolating member is attained.
In the present invention, the connecting portion for observing the pressure in the interior portion of the flexible isolating member is provided and the abnormality of the flexible isolating member is detected.